Technical Field
This disclosure relates generally to control of the motion of camera components and more specifically to the motion of camera components for small-scale cameras.
Description of the Related Art
For high-end miniature cameras, it is common to incorporate ‘auto-focus’ (AF), whereby the object focal distance is adjusted to allow objects at different distances to be in sharp focus at the image plane, to be captured by the digital image sensor. There have been many proposals for achieving such adjustment of focal position.
The most common solution, however, is to move the whole optical lens as a single rigid body along the optical axis using magnets mounted to a voice coil motor base and coil mounted to the optics. Positions of the lens closer to the image sensor correspond to object focal distances further from the camera. Demands on improvements to performance of such miniature cameras are constant, as are demands for continued miniaturization, given the added features and devices added to such mobile devices.
Unfortunately, however, current solutions generate and retain excessive heat for use at the sizes demanded in small form-factor camera platforms, such as cameras in phones, computers, and other multifunction devices. This generation and retention of heat is particularly acute in the long periods of autofocus engagement typical for such cameras, because periods of cooling inactivity are not as likely in the expected field-use scenarios.